IDL 字符串操作

1 字符串拼接

IDL> arr=['My name', 'is', 'QQ']

IDL> print, strjoin(arr) ;直接拼接字符串

My nameisQQ

IDL> print, strjoin(arr,'\t') ;用'\'对字符串进行拼接

My name\tis\tQQ

IDL> print, strjoin(arr,' ') ;用' '空格拼接字符串

My name is QQ

 

2 字符串长度

IDL> print, strlen(arr[0])

           7

IDL> print, strlen(arr)

           7           2           2

3 大小写转换

IDL> print, strlowcase('My name')

my name

IDL> print, strupcase('My name')

MY NAME

 

4 移除空格

IDL> print, strcompress(' My name ', /remove_all) ;移除所有空格

Myname

IDL> str = strtrim(' My name is QQ ', 0) ;移除尾部空格

IDL> help, str

STR             STRING    = ' My name is QQ'

IDL> str = strtrim(' My name is QQ ', 1) ;移除首部空格

IDL> help, str

STR             STRING    = 'My name is QQ '

IDL> str = strtrim(' My name is QQ ', 2) ;移除两端空格

IDL> help, str

STR             STRING    = 'My name is QQ'

 

5 字符比较

IDL> a='My name is QQ'

IDL> b='My name Is WebChat'

IDL> help, strcmp(a,b) ;整个字符串比较

<Expression>    BYTE      =    0  ; 不等

IDL> help, strcmp(a,b,8) ;前8个字符进行比较('My name ')

<Expression>    BYTE      =    1  ;相等

IDL> help, strcmp(a,b,9) ; 前9个字符比较

<Expression>    BYTE      =    0 ;不等

IDL> help, strcmp(a,b,9,/fold_case) ;前9个字符比较(不区分大小写)

<Expression>    BYTE      =    1 ;相等

 

6 字符串查找

IDL> help,strpos('My name is QQ','QL') ;从头开始找首次出现的字符索引

<Expression>    LONG      =           -1 ;没有找到

IDL> help,strpos('My name is QQ','QQ') 

<Expression>    LONG      =           11 ;找到索引

IDL> help,strpos('My name is QQ','QQ',/reverse_search) ;虽然设置了reverse_search, 依旧从头开始找首次出现的字符索引

<Expression>    LONG      =           11

IDL> help,strpos('My name is QQ','is', 7, /reverse_search) ;从索引为7的位置开始,反向寻找'is'

<Expression>    LONG      =           -1 ;没有找到

IDL> help,strpos('My name is QQ','is', 8, /reverse_search) ;从索引为8的位置开始,反向寻找'is'

<Expression>    LONG      =            8 ;找到索引

IDL> help,strpos('My name is QQ','is', 8) ;从索引为8的位置开始,正向寻找'is'

<Expression>    LONG      =            8 ;找到索引

 

7 获取字符串

help, strmid('My name is QQ',8, 2) ;从索引8的位置, 获取两个字符

<Expression>    STRING    = 'is'

 

8 字符拆分

IDL> print, strsplit('My name is QQ',' ') ;基于原有字符中的空格拆分字符串

           0           3           8          11 ;返回拆分后字符串在原字符串的位置索引

IDL> arr=strsplit('My name is QQ',' ',/extract) ;返回拆分后的字符串

IDL> help, arr

ARR             STRING    = Array[4]

IDL> print, arr

My name is QQ

IDL> print, strsplit('My name is QQ',' ',/extract, count=count, length=length) ;返回拆分后字符串数量

My name is QQ

IDL> print, count ;返回拆分后字符串总数

           4

IDL> print, length ;返回拆分后每个字符串的长度

           2           4           2           2

 

9 字符匹配

IDL> str = ['foot', 'Feet', 'fate', 'FAST', 'ferret', 'fort']

IDL> PRINT, str[WHERE(STRMATCH(str, 'f??t', /FOLD_CASE) EQ 1)] ;忽略大小写, 匹配首尾字符为'f'与't', 中间有2个字符的字符串

foot Feet FAST fort

PRINT, str[WHERE(STRMATCH(str, 'f*t', /FOLD_CASE) EQ 1)] ;忽略大小写, 匹配首尾字符为'f'与't', 中间字符不限的字符串

foot Feet FAST ferret fort